The World is Mean, So Your Load Tests Must Be Meaner

It's amazing how your backend service works fine when testing it with curl, postman or a frontend GUI, but fails all over the place when unleashing a mean load testing tool like siege on it:

DB pool exhaustion
HTTP connector settings out of sync with other components
Integrations with 3rd party systems stall
Basically, with any scarce resource you thought the app would recycle when you write connection.close(), will potentially come back and bite you since your app spends longer actually closing it than what you assume in your code.

The world is mean, so prepare your app by using a mean testing tool. My favourite is siege. In addition be an excellent and scriptable shell command, it can sustain heavy load creation much better than e.g. JMeter, which I've on several occations seen freeze up when the going gets rough.

Allows you to create a URI file with all HTTP operations, including POSTing JSON.
Allows passing as many HTTP headers as you want (so, including auth with bearer tokens).
And last, but not least, it works on any platform, any server.

Here's a non-trivial example of using siege for testin both read and write performance of a backend system:

$ siege \
    --concurrent=255 \
    --time 10S \
    --header="Authorization: Bearer eyhunter2.." \
    --header="X-Important-Id-For-App: foo-bar-baz" \
    --content-type=application/json \
    --json-output \
    --benchmark \
    --internet \
    --no-parser \
    --file /tmp/load-test.siege

The contents of /tmp/load-test.siege:

# Service discovery document, generated so can be expensive
http://localhost:8000/openapi.json

# Read book
http://localhost:8000/book/1

# Read a thousand books
http://localhost:8000/book/?count=1000

# Create book
http://localhost:8000/book POST {"title": "The Iliad", "author": "Homer"}

# Create library
attic_name="My loft"
http://localhost:8000/library POST {"name": "The Attic called ${attic_name}"}

As you can see in the library example, siege has rudimentary support for variables too. Read the fine manual with man siege and learn further details about this excellent tool.

Happy load testing!